An integrated system for process control in which a process supervisor procedure (which is preferably the top-level procedure) is configured as a modular software structure with modules which can be revised by a user at any time, without significantly interrupting the operation of the process supervisor. Users can define or redefine modules by editing highly constrained templates. These templates use a standardized data interface (as seen by the user), which facilitates communications with an extremely wide variety of systems. The template set preferably contains highly constrained portions (which are optimized for the most common functions), and also contains pointers to user-customized functions. Thus, rapid set-up and modification are possible, but sophisticated users still have full flexibility to do customization.